AbstractTreatment of poplar wood using glyoxal as a non-formaldehyde cross-linking reagent was investigated. Cross-linking occurred with glyoxal in the presence of the catalysts aluminum sulfate, magnesium chloride, zinc nitrate, maleic anhydride, ammonium dihydrogen phosphate, ammonium persulfate. Ammonium persulfate was found to be the most effective single catalyst, which may be due to the synergistic catalytic effect of NH4+ and S2O82-, Further, catalyst combinations produced higher overall performance in comparison with the single one, and the optimal combination was maleic anhydride and ammonium persulfate. An increase in ammonium persulfate improved wood dimensional stability and anti-leaching properties, but weakened the hydrophobicity and deepened the colour of the modified wood. Considering the balance between anti-swelling efficiency, leachability, and water uptake, the optimum catalyst concentration was 2%. Although the addition of sodium hydroxide into a glyoxal solution can reduce wood discoloration, it may also reduce the modification efficiency.